I'm trying to trace John Casken who I think you are referring to as living in Durham in 1881. He then moved to North Yorks (Hilton nr Yarm) where his wife Mary gave birth to my grandfather! John died aged 41 in 1896. The only record I have of him before 1881 is his marriage to Mary (Fenwick) in 1879 - in the BMD he is recorded as John Casham, but the parish register is clearly signed Casken and says his father was also John, but there is no trace of such a person. The name had led me to suspect a Manx connection, but there could still be all sorts of explanations. If you have any info which might help, please get in touch.